Certain uses of phosphorus-containing flame-retardant components, especially phosphorus in conjunction with halogens are known. For example, Lommel et al., U.S. Pat. No. 1,936,985 (1933), disclose the production of certain phosphorus and phosphoric acid esters of oily consistency which may contain a halogen and which are capable of reducing the flammability of organic materials if incorporated therewith. It is taught that their viscosity increases with increasing carbon content.
Gibbons et al., U.S. Pat. No. 3,732,342 (1973) (incorporated herein by reference), disclose certain bromoether phosphorates. These phosphates were disclosed to be useful as fire-retardant plasticizers for polyvinyl chloride and as a fire retardant for latex resin.
Hamamura et al., Chemical Abstracts, 91:124836a (1979); Maki, Chemical Abstracts, 83:163630h (1975); and Tamazaki et al., Chemical Abstracts, 78:110564e (1973) each disclose certain halogenated etherified phosphorates as in fire-retardant polyester or acrylic fabrics or plastic films; as flame-resistant agents; as halogen-containing phosphates, respectively.
Birum et al., U.S. Pat. No. 3,132,169 (1964) (incorporated herein by reference), disclose the preparation of certain phosphate esters which contain both chlorine and bromine. It is disclosed that polyurethanes, for example, insulating foams and resin bases for curable coatings and adhesives, may be made flame-retardant by the addition of the phosphate esters in amounts from 2 percent to 25 percent by weight of the polyurethane. It is also disclosed that simultaneous plasticizing results and the use of the phosphate esters in the polyurethane foams taught therein (i.e., rigid foams) can increase flexibility and in some applications improve the mechanical properties of the foams.
Fesman, U.S. Pat. No. 4,477,600 (1984), discloses certain polyurethanes with certain phosphonate ethers and antioxidants. It is disclosed that the polyurethanes are low scorch.
Wegner, U.S. Pat. No. 4,275,171 (1981), discloses certain production of flexible flame-retardant polyurethane foams. The foams contain certain halogenated phosphonate and phosphate ester plasticizers.
Waldmann, U.S. Pat. No. 4,172,863 (1979), discloses certain halogen-containing organic phosphorus compounds which contain reactive functional groups and certain fire-retardant polymeric compositions containing the compounds. The polymeric compositions include polyurethanes.
Weil, U.S. Pat. No. 3,955,028 (1976), discloses certain 3-bromo-2,2-bis(bromomethyl)propyloxy phosphorus compounds with reactive functional groups. The compounds are disclosed to be useful to flame retard certain polymers. See, e.g., column 7, lines 35-47.
Ginter et al., U.S. Pat. No. 4,298,709 (1981) (incorporated herein by reference), disclose certain polyhydroxyl polyether phosphorates which may contain halogen. It is disclosed that these phosphorates are useful as flame retardants which react with polyfunctional chain-forming compounds, for example, in production of polyurethanes.
Preston et al., U.S. Pat. No. 4,235,975 (1980), disclose that addition of flame retardants to foam formulations introduces its own peculiar scorch problems.
Mueller-Tamm et al., U.S. Pat. No. 3,093,599 (1963), disclose that properties of suitable compounds for the flame-proofing of plastics include odorlessness and low volatility.
Numerous problems continue to beset the commerical polyurethane foamer who desires to produce a highly marketable flame-retardant foam, especially a slabstock flexible foam. Among these can be
(1) processability; PA0 (2) scorch; PA0 (3) odor; PA0 (4) flame-retardant efficiency; and PA0 (5) cost. PA0 (1) processability; PA0 (2) scorch; PA0 (3) odor; and PA0 (4) flame-retardant efficiency.
Processability may be a function of the number of flame-retardant components needed to be introduced and their physical state upon introduction. Simplicity of the flame-retardant component is desirable. A liquid phase flame-retardant component is often preferred. Low viscosity liquids are desirable because of their ease of introduction into the foam formulation and increased uniformity of distribution throughout the foam. A liquid flame-retardant component having a Brookfield viscosity of about 4000 cP (i.e., centipoise) or below is desirable for processing ease, Flame-retardant components with lower viscosities are preferable for flexible polyurethane foam production. Typically, additive-type flame-retardant components offer better processability over reactive types.
Scorch is typically a yellow or brown discoloration of the flame-retardant polyurethane foam, particularly in the center of the foam sample which is commonly called a bun. Scorch may be indicative of degradation of the foam and occurs mainly in higher water formulations. Increased ambient humidity during foaming may play a part in scorching. Scorch is typically much more of a problem in flexible polyurethane foams in comparison to rigid polyurethane foams, which are commonly also known as insulating foams, and is typically much more apparent in foams from large-scale production runs than in foams from small-scale laboratory tests. One of the reasons for this is the increased production scale itself which may result in heat-transfer difficulties from the exothermic foaming reaction as well as the inherent insulating properties of the polyurethane foam. In commercial production, the bun may reach temperatures of about 100.degree. C. to about 180.degree. C. for several minutes to a few hours. For example, bun temperatures of about 140.degree. C. to about 160.degree. C. for about 15 to 30 minutes may be encountered. See, e.g., The Flexible Polyurethane Foam Handbook, The Dow Chemical Company, U.S.A., Urethanes Department (1984) (incorporated herein by reference) at pp. 19-20. Well controlled small-scale laboratory tests for scorch can be indicative of those flame-retardant flexible polyurethane foams which may not scorch in production. However, the best indication of a non-scorching foam still remains the large-scale commercial-type production.
Odor is a problem of the flame-retardant foam, especially in the flexible polyurethanes containing certain additive-type flame-retardant components. A musty odor may often be difficult to overcome, especially in certain liquid flame-retardant components which are in more flame-retardant-effective formulations.
Flame-retardant efficiency after production may be of concern, especially in certain commercial flame-retardant flexible polyurethane foams having a volatile additive-type flame-retardant component. Lower molecular weight liquid flame-retardant components, although they may have concurrently good processability, may occasion this problem. Higher molecular weight additive flame-retardant components may be employed to help overcome this, but processability may suffer, and it may then become difficult to efficiently obtain a homogeneous distribution of flame retardant in the foam.
Cost is always of concern to the commercial foamer. The cost may be directly linked to the price of the foam components and to the amount of flame-retardant components which desirably and favorably affect solutions to problems such as the first four enumerated.
What is lacking and what is needed in this area is a phosphorus-containing flame-retardant component which when incorporated into a polyurethane foam, especially in a flexible polyurethane foam, may be used to produce a highly marketable flame-retardant polyurethane foam, especially flexible slabstock foam. It is especially desirable that any such flame-retardant component overcome real-world problems which continue to beset the commercial polyurethane foamer such as processability, scorch, odor, flame-retardant efficiency and cost.